Efficacy of Non-Mechanical Surface Organic Matter Reduction Products On a Creeping Bentgrass Research Green.

Excess surface organic matter (OM) compromises soil physical properties and results in a soft, spongy surface more prone to mower scalping and poor playing conditions.  Less disruptive, non-mechanical surface OM practices are an attractive alternative to coring and topdressing because they would cause less surface disruption, improved playability, and increase golfer satisfaction.  Many natural organics and sugar-based products have been applied to greens to speed excess OM biodegradation with mixed results.  This field study, during two growing seasons, evaluated the efficacy of eight treatments including single products or various combinations of a granular poultry meal-based fertilizer, molasses, biostimulants, and liquid iron (Fe) products and were compared to urea alone at 4.9 kg N ha^-1 wk^-1.  Treatments were applied every 7 days to a mature 'Pennlinks' creeping bentgrass [Agrostis stoloniferous L. var. palustris (Huds.)] sand research green.  The research green was core aerified twice annually and received regular topdressing.  Surface (0-25 mm) OM content (g kg^-1), calculated by loss on ignition, surface firmness, using the USGA Tru-Firm, and canopy greenness (CG) were measured.  Additionally, visual turfgrass quality (TQ) and dollar spot incidence were recorded.  Initial OM levels ranged from 52-74 g kg^-1 with no treatment differences.  By November, year two, OM ranged from 28-42 g kg^-1 with very small numerical treatment differences.  There was no difference among treatments for surface firmness.  Higher TQ was associated with the Fe-containing treatments, primarily due to increased CG.  Stimulation in dollar spot was observed for treatments containing molasses, however, a treatment response was inconsistent.  Traditional coring and sand topdressing continues to be the most effective OM management method.